Odorant for refrigeration



Patented Apr. 25, 1933 NITED STATES PATENT OFFICE,

FRANK J. DOBRO VOLNY, OF NIAGARA FALLS, NEW YORK, ASSIGNOR, BY MFSNE AS- SIGNMENTS, TO THE BOESSLER AND HASSIACHER CHEMICAL COMPANY, OF NEW YORK, N. Y., A CORPORATION .OF DELAWARE ODORANT lFOR REFRIGERATION No Drawing. Application filed January 2, 1930, Serial No. 418,166. Renewed September 10, 1931.

I This invention relates to the use of an agent for warning of escape of refrigerant from refrigerating systems and more particularly from systems in inodorous refrigerants are used. If leaks occur in large refrigerating systems, such as multiple-unit, direct expansion installations in apartment houses, relatively high and dangerous concentrations of refrigerant in the air may result. If the refrigerant is not readily detected by its odor, persons breathing air containing it may not become aware of such leaks.

The object of my invention is to make possible the detection of leaks in refrigerating systems operating with relatively inodorous refrigerants by incorporating in the refrigerant a small proportion of one or more of the alkyl mercaptans, substances having strong,

unpleasant odors.

Substances having odorous or irritating properties have heretofore been incorporated v in gases to enable their detection. Practical- 1y any stable odorant or irritant with a suf ficiently high vapor pressure may be used for such purpose. However, for use in a refrigerant, such a warning agent must possess special properties. It must not only 7 have an' appreciable vapor pressure at room temperature, but must also be readily soluble in the refrigerant at the lowest temperature occurring in the refrigerating system, :have a freezing point below this temperature, be stable under conditions occurring in the system, have little or no corrosive effect on metals and must not react with the refrigerant.

I have found that alkyl mercaptans possess properties which make them especially suited for warning agents in refrigerating systems. The proportions I have used range which relatively ing purposes depends on the nature of the re rigerant and the type of refrigerating machine. It may be desirable to produce a stronger warning effect with some refrigerants than with others and this may be done by increasing the mercaptan content. Various types of refrigerating systems may require different proportions of the warning agent. The proportions I prefer to use in a direct expansion refrigerating system are 0.5-1.0% by Weight of alkyl mercaptan in the refrigerant. The mercaptan-may be in troduced in any suitable manner, either before or after charging the system with refrigerant. a

Refrigerants with which alkyl mercaptans may be used as warning agents comprise those which readily dissolve these substances at the lowest temperature occurring in the refrigerating system, and which do not resonable period. v If condensed from about 0.5% to 2.0% byweight of mercaptan'in the refrigerant in the condensed or liquid state. This invention is, however, not limited to these proportions, as it is conceivable that other proportions would be satisfactory, especially under conditions other than those occurring in my experiments.

Ingeneral, the best proportions for warnact with them. Thus, alkyl mercaptans may be used with such refrigerants as methyl chloride, ethyl chloride and other halogenated hydrocarbons, propane and other hydrocarbons.

Alkyl mercaptans may be used with particularly good results as warning agents in a refrigerating system employing methyl chloride. By means of my invention,,persons exposed to concentrations of 0.1% by volume, oreven less, of methyl chloride in air are immediately warned ofits presence. The invention therefore provides a means for warning persons of concentrations of this substance which are far less than any which would endanger the health in any reaor liquid refrigerant containing 0.5 to 1.0% by weight, of ethyl or butyl mercaptan, is allowed to escape into a closed room so as to build up a concentration of 0.05% by volume of gaseous refrigerant in the air,'the-odor of the mercaptan is very marked; at 0.1% of such odorized' methyl chloride in air the odor of the accompanying mercaptan is very strong. 1

A particularly good as warning agents is that the intensity of the odor does not materially decrease on continued exposure; as'is the case with many odorfeature of mercaptans ants. I have found that person occupying a room, in which a vapor containing a mercaptan is slowly accumulating does not-ac quire a tolerance for the odor but is as acutely aware of its increased intensity as if he had entered the room from uncontaminated air. A further advantage is that the same warning effect results from leaks from the high and low pressure sides of a compression type refrigerating system, showing that the alkyl mercaptan does not accumulate in any part of the system to such degree as to render its action ineffectual. The mercaptan itself has no harmful efiects when used as here specified as Warning agents.

Emample 1 A compression type refrigerating ma chine was charged with methyl chloride containing 0.5% by weight of ethyl mercaptan. After the machine had operated two days, measured quantities of the refrigeration vaport'we're released in a closed room. After the air in the test room had been thoroughly agitated by an electric fan, several persons entered and independently noted their reactions to the odor. In the case of all observers, when theair contained as little as 0.5% methyl chloride gas, the accompanyingmercaptan odor was positively identified; and served as a distinct notice or warning. At 1% methyl chloride concentration the mercaptan odor was noted as strong.

E wample 2 i The procedure described in Example 1 was carried out with 0.5% butyl mercaptan in methyl chloride. At 0.5% methyl chloride concentration in the air half of the observers noted the accompanying mercaptan odor as moderateand the'remaindernoted strong;

at 1% methylchloride concentration the odor of the mercaptan was noted as strong and very. strong.

Tests made to determine the eifect of ethyl and butyl mercaptans on iron, brass and copper, under conditions similar to those found in operation of a refrigerating system, for instance, dissolved in a refrigerant grade of methyl chloride and under anhydrous con- I in methyl chloride, operated normally and with no trouble for eleven weeks. A test carried out by the method described in Examples 1 and 2 showed no diminution of warning action at the end of this period.

.taining 0.5% to 2% of ethyl mercaptan.

3. A composition of matter comprising methyl chloride containing an alkyl mercaptan.

4. A composition of matter comprising methyl chloride containing ethyl mercaptan.

5. A composition of matter comprising substantially anhydrous methyl chloride containing 0.5% to 1%' of an alkyl mercaptan."

6. A composition of matter comprising substantially anhydrous methyl chloride containing 0.5 to 1% of ethyl mercaptan.

Signed at Niagara Falls in the county of Niagara and State of New York this 26th day of December A. D. 1929.

FRANK J. DOBROVOLNY.

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